Boiler



Nov. 1, 1932. T E, MURRAY 1,886,214

BOILER Filed March 23, 1927 2 Sheets-Sheet 2 OO OO -/75 OO OQ 4 Oo Oo 14 u i: 16 Q@ /N VENTO/e oMASM//PRAK Patented Nov. l, `1932 UNITED STATES' OFFICE THOMAS E. MURRAY, OE BROOKLYN, NEW YORK; JOsEPH :BRADLEY MURRAY, THOMAS E. MURRAY, JR., AND JOHN E. MURRAY, ExEcUTORs OE SAID THOMAS E. MURRAY, DEcEAsED, AsSIoNORs To METROPOLITAN ENGINEERING COMPANY, A CORPORATION F NEW' YORK :BOILER Application filed March 23, 1927. Serial No. 177,584.

bodiments of the invention.

Fig. 1 is ahorizontal section of a portion of the furnace wall of a boiler;

Fig. 2 is a front elevation of the same;

Fig. 3 is a vertical section of the same;

Figs. 4 and 5 are respectively horizontal sections of modified constructions;

Fig. 6 is a horizontal section on the line 6`6 of Fig. 7 of another modification; j

Figs. 7 and 8 are respectively a front elevation and a vertical section of the same.

In certain previous applications I have described boilers having one or more furnace walls composed of or lined with vertical water tubes with fins in the spaces between them to expose an extended surface to the radiant heat ofthe burning fuel, generall coal dust, oil or other fuel projected in jets rom nozzle burners. I have illustrated herein an arrangement working on the same principle and providing an even greater surface exposed directly to the radiant heat of the burning fuel in the furnace chamber.

The outer portion of the wall may be built l of various materials. As illustrated in Fig. 1 there is a layer of insulating composition 1 (or it may be brickwork) with a hard finish 2 on the outer face and an inner layer 3 'of highly refractory cement.

Within this wall and along one or more sides of the chamber is a row of vertical water tubes 4 connected into the circulation of the boiler. Each tube, in Figs. 1 to 5, has at the they are spaced apart slightly and are tied to the backing by means of small Ts 7 placed between them overlapping their faces and extending back into the cement layer 3 and rods 8 passing through openings in the webs and imbedded in the cement. Eachtube with its attached lin is separate from the others. This permits the slight relative expansion and contraction which is necessary at the high temperatures involved. For high duty boilers, for which the invention is particularly useful, it is important to rovide for such differences in expansion of a jacent tubes. Also, in erection or in replacements, it is important to have each tube with its fin separate.

In building the structure the tubes are first set up with Ts 7 and tie rods 8 in place, and the cement lthen applied and the wall completed by addition of the insulating layer 1 and the hard finish 2. A With' this arrangement the direct radiant heat is applied-to much more than half the circumference of the tubes themselves and to nearly the entire surface of the fins 5 and iianges 6. The result is an extraordinary acceleration of the rate of transfer of heat toA the tubes, and a very rapid circulation of water through them, which is the easier because lof their vertical position. Steam is generated at a correspondingly hi h rate.

The fins and the joint members are made from standard rolled Ts and the tubes are standard boiler tubes, generally seamless steel. The rapid circulation of water protects the tubes from burning out. The T'- shaped -fins are partially protected by the circulating water but they (as well as the small Ts 7) are preferably made of nonoxidizing metal such as steel treated or coated in various known ways.

In the use 'of a furnace thus constructed there is a tendency to deposit on the exposed metal surfaces a coatin of powdery or granula-r mineral matter w lich is highly refractory. This coating serves the double purpose of protecting the metal from being burned out by the high temperature and also of shielding the iia`me against an excessive cooling effect from the metal. It is important particularly with low grades of fuel, to

material. It is generally maintained at thev temperature of incandescence or approximately so, at which temperature the heat of the llames is maintained. This is particularly im ortant where the gases are used to heat additional overhead tubes by convection. Such a coatino is indicated at 9, accumulated on the exposed faces of the ins and the jointmembers. It also tends to accumulate on the tubes. But it is more useful on the fins and their flanges in protecting the back wall from excessive heating.

Instead of relyin entirely on the incidental and automatic epositing of the mineral coating and the maintenance of it on the metal face of the wall, I may provide a permanent coating of this sort at the points desired. This may be done either by spreading or spraying on the metal surfaces lamp-black or similar sticky carbonaceous material, which will hold the mineral deposit produced by the Haines, or by similarly applying a coating of the desired refractory mineral itself.

I have provided also, in connection with the above structure, for carrying the superheater tubes in the furnace chamber and exposing them also to the radiant heat of the burning fuel. Superheater tubes are nested in groups between the fins 5 of adjacent boiler tubes; these superheater tubes being connected up to the other parts of the boiler in well known ways, not illustrated. When the heat is first applied, the superheater tubes, having no steam in them are particularly liable to be burned out. It is important therefore that they be protected by a coating 11 of mineral matter similar to the coating 9.

It is not essential that the entire surfaces of the fins be shielded. The edges farthest from the tubes are most aptgto burn out, and the protection may extend to these remote parts alone. Fi s. 4 and 5 show this idea carried out in di erent ways. In Fig.- 4 a plastic coating 12 is applied to the outermost portions of the flanges 6, leaving the inner portions of such flanges and the webs 5 directly exposed the same as the tubes 4. Also a slight space is left between the edges of thelanges 6, over which the coating 12`extends. In this gure the relative thicknesses of the parts ofv the wall and the dimensions of the fins a/,Ie`

shown somewhat differently from those f/ in Fi 1. Such details are capable of considerab e variation.

According to Fig. 5 the edges of the flanges d 6 are protected by beingfitted into vertical grooves in the edges of a line of tiles 13 constituting the joint between adjacent fins'. Joints of the same sort may be made by plates of Stellite or other high temperature metal lapped across the adjacent edges of the flanges; serving directly to protect the flanges and serving also to accumulate a protective coating where the radiant heat is greatest, that is in line with the spaces between adj acent tubes 4. A.

According to Figs. 6 to 8 a different construction of fin is used. Angular plates 14, 15 have their portions 15 welded in pairs to the back of each tube 4 with the portions 14 extending in line in the same way as the anges ,6 of Fig. 1. This secures lapproximately the saine wide exposure of the fins as in Fig. 1; providing in effect a T-shape with a double web.

In this construction also the exposed faces of the ns are shielded by a coating 16 of refractory mineral matter secured in any of the ways above described. The anges 14 have openings through which the cement 3 passes so as to lock these parts together.

Fig. 7 illustrates the coating 16 extending over only the lower portion of the wall, the metal of the fins being directly exposed above this level. The same variation may be applied to the coatings shown in the other figures. This is to protect the fins in the lower part where the flame is hottest and to get the maximum heating effect above this zone.

With such a protected metal face, the backing of the wall will be kept fairly cool and not subject to the rapid deterioration which would occur without such protection.

The protective coating described may be applied to various other constructions. See for example my co-pending application No. 177,533, filed March 23, 1927.

Various other modifications may be made by those skilled in the art without departing from the invention as defined in the following claims.

What I claim is:

1. A boiler furnace wall of water tubes with fins having edges welded to said tubes at the back, the front half and part of the back half of the tubes being exposed to the radiant heat of the burning fuel and said fins being exposed to the heat within thefurnace, the tubes with their attached fins being separate from one another.

2. The boiler furnace wall of claim 1, said ins having lateral extensions to provide additional exposed surface.

3. The boiler furnace wall of claim 1, said fins having lateral extensions to provide additional exposedv surface extending substantially or approximately across the spaces between adjacent tubes.

4. The boiler furnace wall of claim 1, said fins having lateral extensions to-provide additional exposed surface extending substantially or approximately across the spaces between adjacent tubes and a backing of plastic refractory material.

5. A boiler furnace wallv of water tubes with fins having edges Welded to said tubes at the back, `the front half and part of the back half of the tubes being exposed to the radiant heat of the-burning fuel and said fins being exposed to the heat within the furnace, the tubes with their attached fins being sepa.- rate from one another, and refractory material covering at least a part of the exposed faces of said fins: and serving to shield the ns andto protectthe burning gases from excessive cooling.

6. A boiler furnace wall consisting of vertical tubes `with T-shaped finshaving the edges of their webs welded to the backs of the tubes, the tubes being spaced apart with open spaces between them and extending clear around them to the points at the back where the fins are Welded, and said fins being exposed to the heat within the furnace. -l

7. The boiler furnace wall of claim 1, with a coating of refractory mineral matter permanently adheringto said Ens.

8. A boiler furnace wall which includes Water tubes with external fins, the convex surfaces of the tubes at the inner side of the wall being uncovered and exposed directly to the heat within the furnace, and a refractory mineral matter permanently coating the inner faces of said ins so as to shield them Vfrom excessive heat and to protect the burning gases from excessive cooling. Y

`9. A boiler furnace wall having an outer portion of insulating material at the inner side of which are watertubes having their front half and part of their back half exposed to the gases within the furnace, said tubesbeing slightly spaced away from said outer insulating portion of the wall and having fins extending backward from the tubes .and exposed to the gases within the furnace,

10. The boiler furnace wall of claim 9, said fins extending also laterally beyond the width of the tubes to provide additional exposed surface.

11. The boiler furnace wall of claim 9, said' fins extending also laterally beyond the width of the tubes to provide additional exposed surface extending substantially across the spaces between adjacent tubes. r

In witness whereof, I have hereunto signed my name.

THOMAS E. MURRAY. 

